1. Temperature
- Cell respiration relies on enzymes, which work best at optimal temperatures.
- Higher temperatures increase enzyme activity, speeding up respiration.
- However, if the temperature exceeds the optimum temperature, enzymes can denature and stop working.
During intense exercise, muscles may not get enough oxygen, leading to anaerobic respiration and the production of lactate.
2. Type of Respiratory Substrate
- Different substrates (e.g., glucose, lipids) yield varying amounts of energy.
- Carbohydrates are often used first because they are easy to break down.
- Lipids provide more energy per gram but are metabolized more slowly.
Lipids yield more ATP than carbohydrates, but they require more oxygen to break down.
3. Oxygen Availability
- Oxygen is the final electron acceptor in the electron transport chain of aerobic respiration.
- Limited oxygen forces cells to switch to anaerobic respiration, which is less efficient and produces much less ATP.
- Animal cells produce lactate under low oxygen, while yeast produces ethanol and carbon dioxide.
4. Substrate Concentration
- Higher concentrations of glucose or other substrates can increase the rate of respiration, up to a point.
- Once enzymes are saturated, adding more substrate won’t increase the rate further.
5. pH Levels
- Enzymes involved in respiration have an optimal pH range.
- Deviations from this range can slow down or halt the process.
The Krebs cycle enzymes work best at a slightly alkaline pH (~7.4).
Note- Don’t confuse aerobic and anaerobic respiration.
- Aerobic respiration requires oxygen and produces more ATP, while anaerobic respiration occurs without oxygen and yields less ATP.
Measuring the Rate of Cell Respiration
1. Oxygen Uptake
- Respirometers measure oxygen consumption, which reflects the rate of aerobic respiration.
